Your Cab IRs Are Ruining Your Captures (And You Don't Even Know It)

The Part of Your Signal Chain You're Completely Ignoring

Here's a hot take for you: that $200 pack of premium amp captures you just bought? It's only doing about half the work. The other half is being handled by whatever cab IR you've got loaded up. And if you haven't given that IR much thought, well... that explains a lot about why your tone isn't quite where you want it.

We see it all the time. Somebody grabs a killer set of Tonex captures or Kemper profiles, loads them up, and immediately starts tweaking the amp settings because something sounds "off." Nine times out of ten, the amp capture is doing exactly what it's supposed to do. The problem is the cab IR sitting at the end of the chain, quietly sabotaging everything.

Let's fix that.

What a Cab IR Actually Does (And Why It Matters This Much)

Think of it this way. When you mic up a real guitar cab, the speaker, the microphone, the mic position, and the room are all shaping your tone in massive ways. A Shure SM57 jammed right up against the dustcap sounds completely different from that same mic pulled back three inches and angled off-axis. Add a ribbon mic a foot back and suddenly you've got a whole different animal.

An impulse response captures all of that in a single snapshot. The speaker breakup character, the microphone's frequency curve, the distance, the angle, even a tiny bit of room interaction. It's the last thing your signal hits before it reaches your ears, and it has an enormous impact on what you hear.

So when you load up a NAM capture of a cranked Plexi and it sounds fizzy or harsh, the capture might be perfect. You might just be pairing it with the wrong IR.

The "Stock IR" Trap

Every modeler ships with stock cab IRs. And look, some of them are totally fine. The Kemper's built-in cabinets have gotten way better over the years. Tonex has decent options. But "decent" is doing a lot of heavy lifting in that sentence.

Stock IRs are designed to work okay with everything, which means they're not optimized for anything specific. They're the house salad of guitar tone. Nobody's mad about it, but nobody's excited either.

Here's where it gets interesting. When you start swapping IRs on the same amp capture, you realize just how much of what you thought was the "amp character" was actually the cab all along. That HeadRush clone of a high-gain monster that sounded too dark? Try it with a brighter V30 IR with more presence peak. That vintage Fender capture that was too ice-picky? Pair it with a darker Greenback IR and suddenly it's warm and lush.

The amp capture sets the gain structure, the feel, the dynamics, the compression. But the cab IR sets the EQ character more than almost anything else in your chain. Once you internalize that, you'll never look at your rig the same way.

How to Pick the Right IR (Without Losing Your Mind)

The IR rabbit hole is deep, and you can absolutely lose a whole weekend auditioning 47,000 impulse responses. Don't do that. Here's a framework that actually works.

Start with the speaker type. Different speakers have wildly different personalities. Celestion V30s are punchy and present with that signature upper-mid bark. Greenbacks are warmer, smoother, and more "classic rock" in character. Jensen speakers are chimey and bright, perfect for cleans. Alnico speakers compress in a musical way that's hard to beat for blues. Pick the speaker flavor that matches the tone you're chasing, then narrow down from there.

Pay attention to the mic. An SM57 on-axis gives you the tightest, most aggressive tone. Move it off-axis and things get smoother. A Royer 121 ribbon gives you that fat, round, studio-polished sound. A large-diaphragm condenser opens things up and adds air. Multi-mic blends (like a 57 plus a ribbon) are where the real magic happens, and a lot of pro-quality IR packs ship these pre-blended so you don't have to do the mixing yourself.

Match the IR to the use case. Recording through studio monitors? Room mic blends and multi-mic IRs sound incredible. Playing live through an FRFR? Stick with close-mic, single-mic IRs. They cut through better and don't get muddy in a live room. Using NeuralDSP captures for practice at home through headphones? Try something with a bit of room in it so it doesn't feel so "in your face."

The Mix-Ready Secret: Subtractive EQ on Your IRs

Here's a pro trick that most guitarists never think about. You can EQ your cab IR itself, and that's often way more effective than EQing after the fact.

The move is subtractive. Find the frequencies you don't want and cut them. Got a nasty 3kHz spike that makes everything sound like an angry bee? Notch it out with a tight parametric cut. Muddy low-mids around 300Hz? Pull them down a couple dB. The goal isn't to reshape the IR into something it isn't. You're just cleaning up the rough edges so the amp capture can shine.

This works especially well with Kemper profiles and Tonex captures because you're not fighting against the amp sound. You're refining the last stage of the chain where most of the tonal problems actually live.

Full Chain vs. Amp-Only: Know What You're Working With

This is crucial and a lot of people miss it. Some captures and profiles include the cab in the capture itself (sometimes called "full chain" or "amp+cab" captures), and some are amp-only.

If you're loading a full-chain capture AND a separate cab IR, you're essentially running two cabs in series. That's going to sound weird, thin, and filtered. It's like taking a photograph of a photograph. You lose fidelity fast.

So before you go swapping IRs, figure out whether your capture already has a cab baked in. On the Kemper, you can toggle the cab section on and off. In Tonex, check whether the capture is listed as a "Stomp" (amp only) or "Amp" model type. For NAM captures, this usually depends on how the creator captured it, and it should be noted in the pack description.

When you're using amp-only captures, that's where IR choice becomes absolutely critical. You are the cab now. Everything from the speaker character to the mic choice to the room sound is in your hands. And that's actually awesome, because it means you can pair the same amp capture with ten different IRs and get ten completely different (and usable) tones.

Why This Should Change How You Shop for Captures

Once you understand the amp-vs-cab relationship, it changes how you build your tone library. Instead of buying a new amp capture every time you want a different sound, you can get way more mileage by pairing your existing captures with different IRs.

That Six String Lab pack you bought last month? You've probably only heard it through one or two IRs. Load up a different cab and it's like getting a whole new set of captures for free. Our free packs are actually perfect for experimenting with this, because you can pair them with different IRs and hear just how dramatically the cab shapes the final tone without spending a dime.

Think of it like cooking. The amp capture is your protein. The cab IR is how you season and cook it. Same chicken, vastly different meals depending on whether you're grilling, braising, or frying it. (Yes, we just compared your Plexi to a chicken. We're standing by it.)

A Quick IR Starter Kit

If you're just getting into the IR game, here's a no-nonsense starting lineup that covers most situations:

For high-gain and metal: A V30 4x12, SM57 on-axis. This is your bread and butter. Tight, punchy, cuts through a mix like a laser.

For classic rock and blues: A Greenback 2x12 or 4x12, SM57 slightly off-axis. Warmer, smoother, less harsh in the upper mids. Pairs beautifully with our Kemper profiles of Marshall-style amps.

For cleans and ambient stuff: A Jensen or Alnico speaker, condenser mic, maybe with a touch of room. Open, airy, sparkly. Works great with Tonex captures of Fender-style amps.

For recording: A multi-mic blend (57 + ribbon is the classic combo). These translate to a mix immediately with almost zero additional processing. Killer for tracking with NAM captures or HeadRush clones.

Stop Blaming the Capture

Real talk: if you've been cycling through amp captures trying to find "the one" and nothing ever sounds right, the captures probably aren't the problem. Your cab IR is. It's the most impactful and most overlooked piece of the puzzle, and a single great IR can make a mediocre capture sound professional while a bad IR can make the world's best capture sound like garbage.

So before you go hunting for yet another amp tone, try this instead. Take your favorite capture from Six String Lab and spend an hour just swapping IRs. Change the speaker type. Change the mic. Change the distance. You'll be shocked at how much tone is hiding in captures you thought you already knew.

Your amp capture is only half the equation. Time to give the other half the attention it deserves.